View full sizeThe Huntsville Times/Eric SchultzKris Kimlin, a camera operator, works on the end of a giraffe camera crane during the filming of "Space Warriors" at the U.S. Space & Rocket Center Sunday, Aug. 5, 2012 in Huntsville, Ala. "Space Warriors" is scheduled to be released in Spring of 2013.

HUNTSVILLE, Alabama -- The elfin child star Thomas Horn, “Twilight” heartthrob Booboo Stewart and a dozen or so other youthful cast members on the set of the upcoming film “Space Warriors” are clapping, but their applause isn’t making a sound.

The audio of the clapping will be added in post-production. This allows the actors’ dialogue to be easier to record. Director Sean McNamara, 50, the actors and his crew of about 60 or so are filming a scene depicting a celebration after a “moon buggy race,” and the scene is taking place outside on the U.S. Space & Rocket Center campus, in the shadows of a handful of rockets. A RED hi-definition digital camera suspended from a 30-foot giraffe crane is capturing the action.

“If we try to recreate this anywhere, it would be tens of millions of dollars,” said one of the film’s producers, Jason Netter, 43, of Kickstart Productions. “We’re so happy to be here. Everyone’s been so accommodating here at Space Camp, and the opportunity to shoot here has been just awesome.”

The cast and crew are 13 days into a 25-day shoot at the Space & Rocket Center. The 10-hour production days have been sweaty, thanks to the Alabama summer heat.

McNamara, a hulking but cheerful fellow who’s wearing a desert-style hat for shade and has previous credits including 2011’s “Soul Surfer,” revels in making inspiration films for kids – like “Space Warriors.”

“When I was 12-year-old and saw ‘Rocky,’ it wasn’t about boxing,” McNamara said, “it was about ‘Go out and follow your passion.’ That’s all I want to do – make films that make kids say, ‘Hey, maybe I can do that one day.’ ”

Rocket center spokesperson Tim Hall hopes “Space Warriors” will lead to further film and TV projects here.

“We saw hundreds of phone calls after the (‘Smile as Big as the Moon’) movie aired on ABC and Hallmark,” Hall said. “When this movie makes the big screen in front of tens of millions of people, multiply that. We’re ecstatic. Millions of people who don’t know our story about Space Camp are going to see it and want to come.”

“Space Warriors” is planned for a 2013 theater release. Stewart, 18, said he and his castmates have been keeping loose on the sets with a practical joke they’ve named “nosing.”

“We do it constantly,” Stewart said. “I haven’t been able to do it right, but if someone’s not expecting it, you can walk right behind them and poke them on the back with your nose and they won’t be able to feel it. It’s really funny when someone does it right, because we’re all watching them and everyone’s like, ‘Yes!’ ”

Horn, 14, has enjoyed filming scenes underneath the massive rocket engines inside the space center and digging into the “inner journey” of his character, Jimmy Hawkins. “He starts from a position of where he’ll do anything to get what he wants,” Horn said, “but in the end he learns that lying and scheming have their drawbacks and teamwork and honesty can get you much farther.”